The use of a metal tube for medical devices of the type considered herein is known. Since these devices must be capable of being introduced into a body through natural ducts up to the part to be treated, the tube used therein, at least in its forward or distal portion, must exhibit suitable flexibility to follow the turns of these ducts without damaging them.
Systems for rendering a stiff metal tube flexible have already been proposed, but they have been found capable of being improved further.